title: Evolution of POMC: origin, phylogeny, posttranslational processing, and the melanocortins.
abstract: The proopiomelanocortin (POMC) gene was most likely derived from an ancestral opioid-coding gene following the 1R chordate genome duplication event. During the radiation of the jawless fish, the POMC organization plan emerged multiple melanocortin sequences (α-MSH/ACTH and β-MSH) and a C-terminally extended opioid sequence (β-endorphin). Following the 2R genome duplication event, the γ-MSH sequence was gained. Among the jawed vertebrates, three distinct trends in the evolution of the POMC gene are apparent: the gain of the δ-MSH sequence (cartilaginous fish), the loss of the γ-MSH sequence (ray-finned fish), and the retention of the post 2R POMC organization plan (lobe-finned fish/tetrapods). POMC is synthesized in the pituitary gland and in neurons of the hypothalamus, where an array of posttranslational processing mechanisms, such as endoproteolytic cleavage and N-acetylation, generate distinct sets of end-products in these tissues. A striking feature of the melanocortin end-products is the rigorous conservation of the primary sequence of α-MSH and the first 25 amino acids of ACTH.
authors.affiliation: Department of Biological Sciences, University of Denver, Denver, Colorado, USA. rdores@du.edu
authors.forename: Robert M
authors.initials: RM
authors.lastname: Dores
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Baron
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D006801:Humans; D053486:Melanocortins / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D011333:Pro-Opiomelanocortin / Q000235:genetics*; D011499:Protein Processing, Post-Translational
chemical_list: D053486:Melanocortins; D011333:Pro-Opiomelanocortin